Automatic telephone system



Oct. 13, 1942. B. D. WILLIS AUTOMATIC TELEPHONE SYETEM Filed Feb. '1, 1941 '7 Sheets-Sheet 1 INVENTOR.

BERNARD D.W|LL|S ,dfduy, M

ATTORNEYS Oct. 13, 1942.

Filed Feb. '7, 1941 '7 Sheets-Sheet 2 m3 33832: m: NE x v u m3. n ma 1% 5 1 wfl .5 v PB Lfi l a Q RN AW Na 3 j MN a 0 o o m o-o I |||l.ll.l|lll|lII1I\|.I)I\MQN. mv E .3 m2 Q2 8 a w: N8 ,3.

INVENTOR.

v BERNARD D. WILLIS M W,

ATTORNEYS Oct. 13, 1942. B w s AUTOMATiC TELEPHONE SYSTEM Filed Feb. 7, 1941 7 Sheets-Sheet 3 INVENTORQ BERNARD D. WILLIS I n OWJVM M ATTORNEYS Oct. 13, .1942. B. D. WILLIS f 2,298,909

\ AUTOMATIC TELEPHONE SYSTEM Filed Feb. 7, 1941' '7 sheets-sheep;

- ELSE. lnsulatlorj w JJM 405 45i 460 Auiomailc switch 400 INVENTOR. i BERNARD 0. WILLIS I BY,M7M I ATTORNEYS B. D. WILLIS AUTOMA'LIC TELEPHONE SYSTEM Filed Feb. 7, 1941 '7 Sheets-Sheet 5' Insulation Ins'u/ai/on INVENTOR. BERNARD DIWILLIS ATTORNEYS Patented Oct. 13, 1942 AUTOMATIC TELEPHONE SYSTEM Bernard D; Willis, Oak Park, Ill., assignor to As- I sociated Electric Laboratories, Inc., Chicago,

' 111., a corporation of Delaware Application February 7, 1941, Serial No. 377,835 I I 4 2 Claims." (Cl. 179 -18)" The present invention relates to switching systems and, more particularly, to improvements in automatic'telephone systems of the character of that disclosed in U. S. Patent No. 2,222,131, Ber? nard D. Willis, granted November 19, 1940.

'In an-automatic telephone system of the character of that disclosed in the Willis patent the subscriber-controlled switching apparatus provided for-setting up connections between the various subscriber lines is so connectedsand arranged that it may be selectively controlled by a, single impulse of variable length or time dura tion, as contrasted with conventional subscribercontrolled switching apparatus which is selectively controlled by a variable series of impulses 'oi'.

equal length or time duration.

While the telephone system disclosed in the tion and entirely adequate to handle the traflic in a small exchange, such as a private automatic branch exchange, it is not of sufllciently flexible connection and arrangement to handlethetramc in a large exchange, such as a central automatic exchange. i Accordingly, it is anobject or the present invention to provide'an improved automatic teleconnected and arranged that it is sufficiently flexible to handle the traffic in any exchange, re-

gardless oi the size of the exchange. .Another object of the invention is to provide in an automatic telephone system, an improved tandem switching arrangement, wherein each of mary and secondary movements, an improved arrangement torselectively controlling the primary movement ofthe switch in accordance with the time duration of a single impulse transmitted thereto and, for selectively controlling the secondary movement of the switch automatically.

A further object of the invention is to provide in an automatic switch of the type having primary and-secondary movements, an improved arrangement for selectively controlling both the primary 'and the secondary movements oi" the switch in accordance with the time durations of two successive impulses each-of variable time [duration transmitted thereto.

' Willis patent is thoroughly'satisiactory in opera- In general, the objects set forth above are at- Qtained in accordance with thepresent invention by providing in a telephone system, a calling line, a called. line, a calling device selectively opera- 1 tive repeatedly to transmit a plurality of single phone system of the character noted,which is so impulses of variable-time duration over the calling line, and means including a plurality of tan- 'dem related switches adapted to be, selectively controlled sequentially in accordance with the.

time durations of the impulses for setting up a connection between the calling line and the called line. More particularly, the switches an arranged ina switch train including a selector and a tandem related connector, the selector being so 'connectedand arranged that it is responsive to a first impulse transmitted over the calling line to make a first selection in accordance with the time duration of the first impulse and then the switches is selectively controllable byone or more impulses each duration. Another object of variable length or time individual line selections, which is selectively controllable by a single impulse of variable length or time duration;

Another object of the invention is to provide in an automatic telephone system, an improved connector capable of making both line group and individual line selections,- whi'ch is selectively con,- trollable by a plurality of impulses each oi variable length or time duration.

A further objectof the invention is to provide in an automatic switching system, an improved switching arrangement which is selectively operative upon a constant-speed-vaflable time-interval basis.

A-Iurther object oi. in an automatic switch or the type having priof th invention is-to provide .in an automatic telephone system, an improved "selectorcapable of making both line group and the invention is to provide automatically to make a second selection, and the connector being connected and arranged that it is responsive to second and third impulses transmitted over the calling line to make first and second selections respectively in accordance with the time durations of the second and third V impulses.

- In accordance with one featureof the invention, both the selector and the connector c0n-. stitute an automatic switch of the type having primaryand secondary movements. I embodies means responsive to the transmission 01. a single impulse over an associated circuit for selectively controlling the primary movement thereof in accordance with the time duration of the single impulse and automatic means for selectively controlling the secondary movement thereof, whereby the selector is first operated in its primary movement to select one of a plurality of groups of trunks accessible thereto, and is-thenoperated automatically in its secondary movement' to select any'idleone of the trunks from the previously selected group or trunks; The Y The selector connector embodies means responsive to the transmission of first and second impulses each ated in its primary movement to select one of a plurality of groups of lines accessible thereto and is then operated in its secondary movement to select any individual one of the lines from the previously selected group of lines. The selector embodies busy control apparatus operative in the event all of the trunks in the previously selected group of trunks are busy; while the connector embodies line testingapparatus operative to test the idle or busy condition of the lines selected thereby and then operative to return busy tone current over the associated connection or to project ringing current over the selected line, depending respectively upon the busy or idle condi tion of the selected line. Finally, both the selector and the connector embody release apparatus responsive both to the opening of the associated connection and to false dialing over the associated connection to effect the release thereof.

In accordance with another feature of the invention both the selector and the connector are selectively controlled sequentially in tandem over a calling subscriber line associated therewith by a unique calling device at the calling subscriber switch is operative upon a constant-speed-variable-time-interval basis.

The construction and arrangement of the mechanical switch are disclosed and claimed in the copending divisional application of Bernard" D. Willis, Serial No. 408,053, filed August 23, 1941.

Further features of the invention pertain to the particular arrangement of the mechanical elements of the switches and of the circuit elements of the switches and the system, whereby the above-outlined and; additional operating features are attained.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, to-

gether with further objects and advantages thereof, will best be understood by reference to the substation to which the calling line extends, this calling device being operative repeatedly to alter the condition of the calling line from a given condition and then to restore the calling line to the given condition after a predetermined variable time interval, or to transmit a single impulse of variable length or time duration over the calling line, wherein the time duration is directly controlled in accordance with the digit dialed on the calling device. More particularly, the time interval comprises one or more unit time intervals corresponding to the digit dialed on the calling device.

In accordance with a further feature of the invention both the selector and the connector embody a mechanical switch of unique construction and arrangement; which mechanical switch may be of either of two forms. the mechanical switch comprises a rectangular contact bank and an associated wiper capable of both lateral and longitudinal movements in the respective primary and secondary movements" thereof; while the-second form of the mechanical switch comprises'a semi-cylindrical contact bank and an associated wiper capable of both rotary and longitudinal movements in the respective primaryand secondary movements thereof. Each of the switches comprises shift mechanism for selectively controlling both the primary and the secondary movements thereof and clutch mechanism for selectively controlling both the amount of primary movement and the amount of secondary. movement of the switch. Also, each of the switches is operatively associated with a contlnuously rotating drive shaft which is rotated at a substantially constant speed and comprises drive control mechanism including a cylindrical spiral connection, whereby both the primary movement and the secondary movement of each switch is effected at a constant rate. Thus, each movement of each switch is effected at a constant rate for a variable time interval, whereby each following specification taken in connection with the accompanying drawings, in which Figure l is a fragmentary plan view of one form of an automatic switch constructed and arranged in accordance with the present invention; Fig. 2 is a fragmentary end elevational view of the switch shown in Fig. 1; Fig. 3 is a fragmentary side elevational view of the switch shown in Figs. 1 and 2; Fig. 4 is a fragmentary plan view of a modified form of an automatic switch constructed and arranged in accordance with the present invention; Fig. 5 is a fragmentary side elevational view of the switch shown in Fig. 4; and Figs. '6 and 7, taken together, illustrate diagrammatically an automatic telephone system connected and arranged in accordance with the present invention.

Referring now. more particularly to Figs. 1 to 3, inclusive, of the drawings, there is illustrated a first form of an automatic switch I00 embodying the present invention, which comprises a substantially U-shaped support IOI including a flat bottom wall I02 and two longitudinally spacedapart upstanding end walls I03 and I04, and an operating shaft I05 suitably journaled in bearings provided in the end walls I03 and I04. ,Also, the switch I00 comprises 'a longitudinally movable carrlage I06 slidably supported upon two laterally spaced-apart guide rods I01 and I08 arranged in substantially parallel relation and extending longitudinally between the end walls I 03 and I04 of the support IOI. More particularly, two tubular bushings I 09 and H0 respectively surround the guide rods I01 and I08 and are respectively fixed in openings provided in the opposite sides of the carriage I06, thereby to facilitate The operating shaft I05 comprises an enlarged cylindrical section III disposed intermediate the ends thereof, which enlarged section III has a longitudinally extending spiral or helical groove II! cut in the outer surface thereof. Also, the enlarged section III of the operating shaft I05 carries a tubular member I I3 on the outer surface thereof, a pin I I4 being fixed to the tubular member II! and projecting into the spiral groove III cut in the outer surface of the enlarged section II I, for a purpose mor fully explained hereinafter. The tubular member H3 comprises a sprocket wheel II5, a ratchet wheel Hi and an annular flange I", the sprocket wheel H5 and the ratchet wheel I I6 being separated by an annug member H3 and the ratchet wheel H9 and the annular flange I I1 being separated by an annular groove 9 formed in the surface of the tubular member II3.

The upper central portion of the carriage I09 has a substantially semicircular recess I formed therein, thereby to provide upstanding side walls disposed in the annular groove I I9 formed in the tubular member II3. Also, the carriage I06 comprises-a laterally extending shelf "I2I having a longitudinally extending slot' I22 formed therein. Further, the carriage l-06 carries two upstanding bifurcated lugs I23 and I24 on the opposite sides thereof which are respectively arranged in straddling relation with the guide rods I01 and I09.-

Two sprocket wheels I25 and I26 are rotatably mounted upon the guide rods I01 and I09, respectively, the sprocket wheel I25-being arranged between one end of the tubular bushing I09 and the lug I23, andthe sprocket wheel I26 being arranged between one end oithe tubular bushing I I0and the lug I24.

.Further, the switch I00 comprises a laterally movable slide I21 carrying a contact controlling member IOA in the form of a wiper set. At this point it is noted that the control wiper of the .wiper set IOA is of the bridging type; while the line wipers thereof are not of the bridging type, this arrangement being utilized for a purpose more fully explained hereinafter. The slide I21 comprises two side pieces I29 andl30 between which the individual wipers of the wiper set IOA are clamped, by two screws I3I, the individual wipers of the wiper set IOA being insulated from each otherand from the slide I21 by interposed strips of insulation I32. Also, the slide I21 com.- prises a substantially T-shaped carrying piece I33 arranged in the slot I22 formed in the shaft I2I of the carriage I06, the stem of the carrying piece I33 being securely clamped to thevwiper set IOA by the screws I3I.

The head of the carrying piece I33 is securely clamped to an endless chain I34, comprising a plurality of individual links flexibly connected together, by an arrangement including a plate I35 and'two screws I36. The endless chain I34 is arranged in meshing relation with the sprocket wheel II5, which constitutes a driving sprocket wheel, and the two sprocket wheels I25 and I26, which constitute idler sprocket wheels. Further, the slide I21- carries two guide members I31 arranged inspaced-apart relation which are utilized for a purpose more fully explained hereinafter. Also, the side pieces I29 and I30 of the slide I21 are respectively provided with guiding projections I39 and I39 adjacent the upper ends thereof which cooperate with the slot I 22 provided in the shelf I2I of the carriage I09, in order positively to guide the lateral movement of the slide I21 with respect to the carriage I06. Finally, the side pieces I29 and I30 of the slide I21 respectively carry contact control projections I40 and I 4| adjacent the lower ends thereof, for a purpose more fully explained hereinafter.

Further, the switch I00 comprises a unitary first contact set in the first row of contact sets I43 beingindicated at 20A. The individual rows of contact sets are suitably secured together by an contact bank I42 suitably secured in a recess provided in the bottom wall I 02 or the support IN, the end wallv I04 of the support IOI having a connecting recess provided therein in orderto facilitate placement and removal of the contact bank I42; The contact bank I42 comprises eleven laterally spaced-apart andlongitudinally extending rows of contact sets, the first row of contact sets being indicated at I43. Each row of contact sets comprises eleven individual contact sets, the

arrangement comprising a number of laterally extending screws I44. Also, the individual contacts in each contact set in each row of contact sets are insulated from each other by a plurality of longitudinally extending interposed strips of insulation I45 and I46, the insulatingstrip I49 being centrally disposed with respect to the row of contact sets and constituting a guide strip.

Further, the switch I00 comprises an arrangement including a shift magnet 30A for controlling the movements of the carriage I06'and the slide I21. The shift magnet 30A comprises a core I41, a field element I49 ,and a movable armature I49, the armature I 49 being pivotally mounted on the outer end of the field element I49 by a pivot pin I50. Also, the core I41 carries an operating winding I5I and a copper sleeve I52, the copper sleeve I52 rendering the armature I49 slow to release after the operatingwinding I5I has been deenergized. The core I41 is suitably secured to a bracket I52 which in turn is suitably secured to the end wall I03 of the support IN by an arrangement comprisingtwp screws I53. The armature I49 is normally biased in a counterclockwise direction about the pivot pin I50, as viewed in Fig. 2, by an arrangement including a coil spring I54 extending between the armature I49 and the field element I48. The armature I49 comprises an upwardly and outwardly extending finger I55 which normally projects into the annular groove II9 formed in the outer surface of thetubular member II3. Also, the armaturel49 comprises,

an outwardly extending arm I56 which supports the outer end of a guide bar I 51, the guide bar I51 being substantially triangular in cross-section. The inner end of the guide bar I51 is pivotally 'mounted by a pivot pin I 58 to a bracket I59 which in turn is suitably secured by an arrangement,

; wise direction about the pivot pin I59, as viewed in Fig. 3, into engagement with one of the notches provided in the ratchet wheel II6 carried by the tubular member I I3, for a purpose more fully explainedhereinafter.

Further, the switch I00 comprises four sets of switch springs 40A, 50A, 60A and 10A, the individual switch springs in the set of switch springs 40A being suitably secured to the bottom wall I02 of the support IOI and insulated from each other, and the individual switch springs in the set of switch springs 50A being suitably secured to the bottom wall I 02 of the support IOI and insulated from each other. Also, the individual switch springs in the set of switch springs 60A are suitably secured to a bracket I6 I suitably fixed to while the set of switch springs 50A constitutes a first motion limit switch cooperating with the contact control projection I4I provided on the lower end of the side piece I30 carried by the slide I21. a second motion normal switch cooperating with The set of switch springs A constitutes the shelf I2I of the carriage I06; while the set of switch springs 10A constitutes a second motion limitswitch cooperating with the shelf I2I of the carriage I06. Also, a set of switch springs 35A is operativeiy associated with the armature I49 of the shift magnet 30A, the individual switch springs of the set of switch springs 85A being suitably secured to the field element I48 of shift magnet 80A. Further, the individual switch springs of the set of switch springs 35A are suitably insulated from each other and from the end wall I03 of the support IOI.

Further the switch I comprises a driving arrangement including a go magnet 80A, a stop magnet 90A, a spiral leaf spring I62 and a drive shaft IA. The spiral leaf spring I62 is wound around the enlarged section I II of the operating shaft I05, one end of the leaf spring I62 being secured to the enlarged section I II and the other end of the leaf spring I62 being secured to a stud I64 anchored to the end wall I04 of the support IN. -The outer end of the operating shaft I05 carries a tubular collar I65 slidably mounted thereon, a pin I66 being fixed to the operating shaft I05 and arranged in a longitudinally extending slot I61 formed in. the tubular collar I65. The outer end of the tubular collar I65 carries an annular flange I68 formed of magnetic material. The go magnet 80A comprises an operating winding I69 and a magnetic field element I10, the field element I being arranged in operative relation with respect to the annular flange I68. Similarly, the stop magnet 90A comprises an operating winding HI and a magnetic field element I12, the field element I12 being arranged in operative relation with respect to the annular flangeI60. The go magnet 80A is supported by a bracket I13 suitably secured to the end wall I04 of the support IOI; while the stop magnet 90A is supported by a bracket I14 suitably secured to the end wall I04 of the support IOI. Further, a stub shaft I15 is suitably journaled in a bracket I16 which is suitably secured to the bracket I13. The inner end of the stub shaft I15 carries an annular drive plate I11 formed of resilient material, such as rubber, leather or the like, which cooperates with the annular flange I68. The outer end of the stub shaft I15 carries a bevel gear I18 arranged in driven relation with respect to an associated bevel gear I19 carried by the drive shaft I5A. It is noted that the drive shaft I5A is common to a plurality of switches of the character of the switch I00 and is suitably journaled in an external support I80. Preferably, the drive shaft I5A is driven in a counterclockwise direction, as viewed in Fig. 1, by a constant speed motor, not shown, such as a synchronous motor, whereby the speed of rotation of the drive shaft I5A is maintained within extremely close limits. It is noted that the bevel gear I18 is arranged in constant meshing relation with the bevel gear I19, whereby the stub shaft I15 is constantly driven in a clockwise direction, as viewed in Fig. 2, by the drive shaft I5A.

At this point it is noted that the switch I00 as a whole is supported in cooperating relation with the drive shaft I5A upon an'external support, not shown, whereby the bevel gear I16 is arrangedin meshing relation with the bevel gear I19, as previously noted. Also, the switch I00 may be removed asa whole from its external support relative to the drive shaft I5A, thereby to facilitate replacement or repair thereof. Further, in this connec-.

support IIII of the switch I00 may be moved relative thereto; on the other hand, the contact bank I42 may be fixed to the support IOI of the switch I 00 if desired. I

When the switch I00 is completely released the winding I69 of the go magnet 80A and the winding I1I of the stop magnet 90A are deenergized; the operating shaft I05 is biasedin a counter clockwise direction, as viewed in Fig. 2, by the spiral leaf spring I62; and the stub shaft I15 is driven at a constant speed in the clockwise direction, as viewed in Fig. 2, by' the constantly ro tating drive shaft I5A. When the switch I00 is thus completely released the tubular collar I65 occupies its retracted position toward the left, as viewed in Fig. 3, whereby the annular flange I68 completely disengages the annular drive plate I11. Also, at this time, the slide I21 occupies its completely retracted position toward the right, as viewed in Fig. 2, with respect to the carriage I06, thereby to retain operated the first motion normal switch A. Finally, at this time, the carriage I06 occupies its completely retracted position toward the left, as viewed in 'Fig. 3;

thereby toretain operated the second motion normal switch A.

In order to operate the switch I00, thereby to cause the wiper set IOA to select a particular tion, it is pointed out that the contact bank I42 I may also be supported externally, whereby the group or row of contact sets, the winding I69 of the go magnet A is first energized and retainedenergized for a corresponding given time interval, depending upon the speed of operation of the switch I00 relative to the speed of rotation of the stub shaft I15, this given time interval comprising one or more unit time intervals, as explained more fully hereinafter; at the conclusion ofthis given time interval the winding I69 of the go magnet 80A is deenergized and the winding I1I of the stop magnet A is energized. When the winding I68 of the go magnet 80A is thus energized the field element I10 thereof attracts the annular flange I 68, thereby to cause the annular flange 168 to move toward the right, as viewed in Fig. 3, into frictional engagement with the annular drive plate I11, the pin and slot connection I66I61 between the operating shaft I05 and the tubular collar I65 accommodating this movement of the tubular collar I65 and the annular flange I68 carried thereby. When the annular flange I68 is thus moved by the go magnet 80A into frictional engagement with the anrotated in a clockwise direction, as viewed in Fig. 2, with the stub shaft I15, thereby to cause the spiral leaf spring I62 to be wound up.

, .At this time, the winding -I5I of the shift mag net 30A is deenergized, whereby the armature I49 occupies its normal position, being biased in a ounterclockwise direction about the pivot pin as viewed in Fig. 2, by the coil spring I54. Accordingly, the finger I55 carried by the armature I 49 is disposed in the annular g'roove' H9 provided in the outer surface of the tubular member I I3, thereby positively to prevent longitudinal movement of the tubular member H3 along the the spiral groove II2 cut in the outer surface of the-enlarged section I II thereof acts upon the pin I I4 carried by the tubular member II3, thereby to lock the tubular member II3 to the enlarged section III of the operating shaft I05 for rotathe sprocket wheel I I5 acting as a driving sprocket wheel and the sprocket Wheels I and. I26 acting as idler sprocket wheels. As the endless chain I34 is rotated in a clockwise direction the lower portion thereof is moved from the right toward the left, as viewed in Fig. 2, thereby to cause the slide I21 to be moved in guided relation with respect to the slot I22 provided in' the shelf I2I of the carriage I06. As the slide I21 is moved from the right toward the left, as viewed in Fig. 2, the wiper set I 0A is moved from its normal position at the right of the carriage I06 toward'its off-normal position at the left of the carriage I06. As the slide I21 is thus moved it passes the outer ends of the various rows of contact sets, without engagement therewith, whereby the wiper set IOA is moved progressively to select the various groups or rows of contact sets in a continuous motion and at a uniform speed.

The speed of rotation of the operating shaft I05 is so proportioned relative to the diameter of the sprocket wheel II5 and the lateral spacing between'the rows of contacts sets that, at the conclusion of a given unit time interval, the wiper set IOA occupies a position in longitudinal alignment with respect to the first row of contact sets I43; and at the conclusion of any number of unit time intervals between I and II the wiper. set IOA occupiesa position in longitudinal alignment with respect to a corresponding row of contact sets. Thus, at the conclusion of the first,

second,etc., and eleventh unit time intervals the wiper set IOA occupies positions respectively dis- 'tubular collar. I65 and the annular fiange I66 carried thereby to be moved from the right toward the left, as viewed in Fig. 3,'the pin and slot connection I66' -I61 between the operating shaft I05 and the tubular collar I65 facilitating this movement. At this time the winding I1I of the stop magnet 90A is retained energized, thereby to retain the annular flange I68out of engagement with the annular drive plate I11 and in locked engagement with the field element I12. As long as the winding I1l of the stop magnet 90A is retained energized the annular fiange I68 is retained in locked engagement with respectto the field element I12, thereby toretain the spiral. leaf spring I62 in its wound condition and to prea vent unwinding thereof and the consequent rotation of the operating shaft I05 in acounterclockwise direction, as viewed in Fig. 2, in a manner more fully explained hereinafter,

At the conclusion of the movement of the slide 121 from the right toward the left, as viewed in Fig. 2', with respect to the carriage I06, which motion constitutes the first motion of the switch I 00, the winding I5I of the shift magnet A is energized. When the winding I5I of the shift magnet 30A is thus energized the armature I49 is attracted and rotated in a clockwise direction about the pivot pin I50, as viewed in- Fig. 2, against the bias of the coil spring I54. When the armature I49 is thus operated the finger I55 carried thereby is moved out of engagement with the annular groove II9 provided'in the outer surface of the tubular member H3, thereby to unlock the tubular member ,I I3 for longitudinal vided in the ratchet wheel II6, thereby to lock.

the'tubular member I I3 against rotation with the operating shaft I05.

At this point it is noted that the winding I5I of the shift magnet 30A is energized substantially simultaneously with the deenergization of the winding I69 of the go magnet 80A and the en- .ergization of the winding. I1I of the stop magnet 90A; whereby the outer end of the guide bar I51 is moved into engagement .with one of the notches provided in the ratchet wheel II6 prior to the time thatthe annular flange I68 is moved into locked engagement with the field structure I12'of the stop magnet 90A. During this brief interval of time the spiral leaf spring I62 tends to unwind, thereby to rotate the operating shaft I05 in a counterclockwise. direction, asviewed in Fig. 2. However, the spiral leaf spring I62 is prevented from unwinding and the position 6f the operating shaft I05 is precisely centered by the action of the outer end of the guide bar I51 as it is forced by the arm I56 carried by the armature I49 into .one of the notches provided in the ratchet wheel I I6. This arrangement not only positively prevents unwinding of the helical leaf spring I62, as previously explained, but it also positively insures that the .wiper set IOA occupies a position in precise longitudinal alignment with respect to the selected row of contact sets.

Also, when the armature I49 of the shift magnet 30A is thus operated the set of switch springs 35A is operated for a pu'rposemore fully explained hereinafter.

After the switch I00 has been operated in the manner described above, thereby to select one of the rows of contact sets, in order further to operate the switch I00 to select a particular contact set in the previously selected row of contact sets, the winding "I of the stop magnet 90A is first deenergized and the winding I69 of the go magnet A is energized for a corresponding given time interval depending upon the-speed of operation of the switch I00 relative to the speedyof rotation of the stub shaft I15, this given time interval comprisingv one or more unit time intervals, as previously explained. At the conclusion of this given time interval the winding ther wound up.-

At this time, the winding I5I of the shift magnet 30A is energized. and the armature I40 occupies its operated position, thereby to retain the guide bar I51 in engagement with the notch provided in the ratchet wheel II6 carried by the tubular member H3 in order positively to prevent rotation of the tubular member II3 with the operating shaft I05. Accordingly, at this time, the spiral groove II2 cut in the outer surface of the enlarged section III of the operating shaft I05 acts upon the pin. II4 carried by'the tubular member 3', thereby to cause the pin II4 to ride in the spiral .groove II2. As the pin II4 carried by the tubular member II3 rides in the spiral groove II2 cut in the outer surface of the enlarged section III of the operating shaft I05, the tubular member I I3 is slid longitudinally along the enlarged section III from the left toward the right, as viewed in Fig. 3. As the tubular member H3 is slid from the left toward the right, as viewed in Fig. 3, the notch provided in the ratchet wheel II6 carried thereby slides in engagement with the guide bar I51, thereby positively to prevent rotation of the tubular member H3 and continues sliding thereof along the enlarged section III of the operating shaft I05.

As the tubular member 3 is slid longitudinally along, the outer surface of the'enlarged section III of the operating shaft I05 from the left toward the right, as viewed in Fig. 3, the carriage I06 ismoved therewith due to 'the fact that the walls adjacent the semicircular'recess I provided in the upper portion thereof straddle the annular groove II6 provided in the outer surface of the tubular member H3. Accordingly, the carriage I06 is slid .longitudi nally with the tubular member I I3 from the left toward the right, as viewed in Fig. 3, the tubular members I09 and IIO secured to the opposite sides of the carriage I06 respectively sliding along the guide bars I01 and I06. As the carriage I06 is slid longitudinally from the left toward the right, as viewed in Fig. 3, the sprocket wheels I25 and I26 are slid therewith along the guide bars I01 and I08, respectively, andthe slide I21 is moved therewith. When the slide I21 is moved from the left toward the right, as viewed in Fig. 3, the spaced-apart guide members I31 of the wiper set IOA carried thereby received the guide strip I46 of the selected row of contact sets therebetween, thereby positively to guide the wiper set IOA in its sliding movement with re.- spect to the associated row of contact sets. As

the wiper set IOA is thus moved from the left toward the right, as viewed in Fig. 3, it progressively engages the individual contact sets in the previously selected row of contact sets. As previously noted, the line wipers of the wiper set IOA successively engage and disengage the line contacts in the associated contact sets; while the control wiper bridges the control contacts in the associated contact sets, for a purpose more fully explained hereinafter. I

The speed of rotation of the operating shaft I05 is so proportioned relative to the pitch of the spiral groove II2 cut in the enlarged section II I thereof and the longitudinal spacing between the individual contact sets in the row of-contact sets that, at the conclusion of a given unit time interval, the wiper set IOA engages the first conof unit time intervals between I and II, the wiper set IOA engages a corresponding individual contact set in the previously selected row of'con- At the conclusion of the given time interval the winding I69 of the go magnet A is deenergized and the winding I1I of the stop magnet 00A is energized, as previously noted, whereupon the fleld element I12 of the stop magnet 00A attracts the a'nnular'flange I68, thereby to lock the spiral leaf spring I62 against unwinding andthe consequent rotation of the operating shaft I05 in a counterclockwisedirection, as

viewed in Fig. 2. v At-this time, the wiper set I 0A has selected a the first time interval mentioned, and a particular contact set in the selected row of contact sets, corresponding to 'the second time interval mentioned, thereby to establish a connection befrom its normal position at the right toward the left,'as viewed in Fig. 2, the first motion normal switch 40A is operated. In the event that the d slide I21 is moved laterally from the right toward the left, as viewed in Fig. 2, to a position disposed in longitudinal alignment with the eleventh row of contact sets, the first motion limitswitch 50A is operated. Similarly, during the second motion of the switch 100, when the carriage I06 is moved longitudinally from its normal position at the left toward the right, as viewed in Fig. 3, the second motion normal switch 60A is operated. In the eventthat the carriage I06 is moved longitudinally from the left toward the right, as viewed in Fig- 3, into engagement with the eleventh contact set in the previously selected row of contact sets, the second motion limit switch 10A is operated.

In order completely to release the switch I00 after it has been fully operated in the manner previously explained, it is only necessary to de- 4 operating shaft I05 in a counterclockwismdirec tion, as viewed in Fig. 2. At this time, the wind.- ing I5I of the shift magnet 30A is retained energized, thereby to retain the armature I49 thereof in its operated position. The operated armature I49 retains the guide bar I51 in the associated notch provided in the ratchet wheel I I6 carried by the tubular member H3, in the manner previously explained. Accordingly, as the operating shaft I 05 isrotated in a counterclockwise direction, asviewed in Fig. 2, the tubular member I I3 is slid longitudinally along the outer surface of the enlarged section III of the operating shaft I05 from the right toward the left, as viewed in Fig. 3, .due to the cooperation between the pin II4 carried by the tubular member H3 and the associated engaged spiral grcove II2 cut in the particular row of contact sets, corresponding to.

. of the support 40L drical side wall 4| I, an annular bottom wall 2 outer surface of the enlarged section III of the operating shaft I05, in the manner previously explained. a

When the tubular member H3 is returned to its normal position and, consequently, the carriage I06 to its normal position at the left, as viewed in Fig. 3, the winding I5I of the shift magnet 30A is deenergized, whereupon the armature I49 is released and rotated in a counterclockwise direction about the pivot pin I50, as viewed in Fig. 2, by the coil spring I54. When the armature I49 is thus restored the finger I55 carried thereby is returned into the annular groove 9' disposed in the outer surface of the tubular member II3, thereby to lock the tubular member II3 against longitudinal sliding on the outer surface of the enlarged section III of the operating shaft I05 incident to the next cycle of operation of the switch I00. Also, when the armature I49 is thus released the outer end of the guide bar I51 is lowered out of engagement with the associated notch in the ratchet wheel II6, thereby to unlock the tubular member H3 for rotation, in a counterclockwise direction, with the operating shaft I05. The spiral leaf spring I62 then rotates the operating shaft I05 andthe tubular member 3 in a counterclockwise direction, as viewed in Fig. 2, whereupon the endless chain I34 is rotated in a counterclockwise direction, in order to restore the slide I2l to its normal position at-the right, as viewed in Fig. 2.

When the carriage I06 is returned toits normal position at the left, as viewed in Fig. 3, the

second motion normal switch 60A is operated;

and when the slide I2! is moved to its normal position at the right, as viewed in Fig. 2, the first motion normal switch 40A is operated. Of course, the second motion limit switch 10A is operated when the carriage I06 is movedfrom its final right position, as viewed in Fig. 3, in the event that the carriage I06 was so moved as to operate the second motion limit switch 10A initially; similarly, the first motion limit switch 50A is operated when the slide I2! is moved from its final left position, as viewed in Fig. 2, in the event that the slide I21 was so moved as to operate the first motion limit switch 50A initially. Also, when the ,armature I45 of the shift magnet 30A is released the set of switch springs 35A is operatedin an obvious manner. At this time, the switch I is completely released and available for further use.

Construction ohd operation of the modified form of the automatic switch Referring now more particularlyto Figs. 4 and of the drawings there is illustrated a modified form of an automatic switch 400 embodying the present invention, which comprises a support40l and an annular top wall 4I3 suitably secured together to provide a rigid construction. The carriage 4I0 surrounds the operating shaft 406 and is adapted for longitudinal sliding movement thereon, the operating shaft 406 extending through aligned slide bearings respectively provided inthe annular bottom wall M2 and the annular top wall M3. The carriage M0 is operatively connected to the operating shaft 406 by an arrangement comprising a pin 4I4 secured of the bridging type, this arrangement being utilized for a purpose more fully explained hereinafter. The individual wipers of the wiper set IOB are suitably secured together and to the top wall 4I3 of the carriage 4I0 and are suitably insulated from each other and from the top wall M3 by interposed strips of insulation, not shown. Also, the switch 400 comprises a unitary contact bank 4I6, including a semi-cylindrical support-'- ing plate 4II suitably secured to theside walls '402 and 403 of the support l and eleven circumferentially spaced-apart and longitudinally extending rows of contact sets, the first row .of

including side walls 402 and 403, a rear wall 404,

' a bottom wall 405, and an operating shaft 406.

shaft 406 being suitably journaled in a step bearing 401 suitably fixed to the bottom wall 405 The upper end of the operating shaft 406 is suitably'journaled in a bearing collar 408 which in turn is suitably fixed in an opening provided in a transverse angle plate 409- extending between and suitably secured to the side walls 402 and 403 of the support 40I. Also, the switch 400 comprisesa rotatable and lo'ngi-' tudinally slidable carriage 0 including a cylincontact sets being indicated at 4I8. Each row of contact sets comprises eleven individual contact sets, the first contact set in the first rows of contact sets 4I8 being indicated at 203. The individual row of contact setsare suitably secured in radially disposed openings 9 provided in the semi-cylindrical supporting plate 4H. Also, the individual contacts in each contact set in each row of contact sets are insulated from each other by a plurality vof longitudinally extendinginterposed strips of insulation 420 and 42I, the insulating strip 42I being centrally disposed with respect to the row of contact sets and constituting a guide str'ip. At this point it is noted that the individual wipers in the wiper set 10B are arranged in pairs; and the individual contacts in each contact set in each row of contact sets are arranged in pairs; whereby each pair of wipers in the wiper set W3 is adapted to shunt or connect together a corresponding pair of individual contacts in each contact set in each row of contact sets.-

Further, the switch 400 comprises an arrangement including a shift magnet 303 for controlling the rotary and longitudinal movements of the carriage MD. a core 422, a field element 423 and a movable armature 424, the armature 424'being pivotally mounted on the outer end of the field element 423by a pivot pin 425. Also, the core 422 carries ,an operating winding 426 and a copper sleeve 421, the copper sleeve 42'! rendering the armature 424 slow to release after the operating winding 426 has been deenergized. The core 422 and the field element 423 are suitably secured to a bracket 428 which in turn is suitably fixed to the side wall 403 of the support 40I. Further, the field element 423 carries a set of switch springs 353 which is operatively associated with the armature 424, thereby to bias the armature 424 in a counterclockwise direction about the pivot pin The shift magnet 303 comprises 425, as viewed in Fig. 5. Finally, the armature 424 carries an operating arm 428, the outer end of which is disposed below the bottom wall 2 of the carriage 410. At this point it is noted that the armature 424 is adapted to be rotated in a clockwise direction about the pivot pin 425, as viewed in Fig. 5, thereby to cause the operating arm 429 thereof to lift or slide the carriage 4l0 longitudinally of the operating shaft 406. Finally, in this connection, it is noted that the upper end of the spiral groove 4l5 cut in the outer surface of the cylindricalside wall 4 of the carriage 4 I terminates in a substantially straight portion 430 which is normally disposed in engagement with the pin 4 carried by the operating shaft 406. Accordirmly, it will be understood that when the carriage M0 is lifted or slid longitudinally of the operating shaft 406 the pin 4 carried by the operating shaft 406 rides out of the straight portion 430 of the spiral groove 5 into the spiral or'helical portion thereof, in an obvious manner.

Further. the switch 400 comprises four sets of switch springs 40B, 50B, 60B and B, the individual switch springs in the set of switch springs 40B being suitably secured to a trans- .verse bracket 43l extending between and suitably fixed to the side walls 402 and 403 of the support 4M and insulated from each other, and the individual switch springs in the set of switch springs 50B being suitably secured to the bracket 43| and insulated from each other. Also, the indivdual switch springs in the set of switch springs 60B are suitably secured to the bracket 43! and insulated from each other. Finally, the individual switch springs in' the set of switch springs 10B are suitably secured to the plate 408 and insulated from each other. The set of switch springs 40B constitutes a first motion normal switch cooperating with a projection 433 fixed to the outer surface of the cylindrical side wall 4H of the carriage 0; while the set of switch springs 50B constitutes a first motion limit switch cooperating with'the projection 433.' The set of switch springs- 60B constitutes a second motion normal switch cooperating with the'top wall 3 of the carriage 410; while the set of switch springs 10B constitutes a' second motion limit switch cooperating with the top wall 3.

Further, the switch 400 comprises a driving arrangement including a go magnet 803, a stop magnet 9013, a spiral leaf spring 434 and a drive shaft I5B. The spiral leaf spring is wound around the operating shaft 406, one end of the leaf spring 434 being secured to the operating shaft 406 and the other end of the leaf spring 434 being secured to a stud 435 anchored to the bottom wall 405 of the support MI. The upper end of the operating shaft 406 carries a tubular collar 436 slidably mounted thereon, a pin 431 being fixed to the operating shaft 406 and arranged in a longitudinally extending slot 438 formed in the tubular collar 438. The lower end of the tubular collar 436 is normally supported upon the bearing collar 408. The outerend of magnet 80B is supported by a bracket 445 suitably secured to a transverse angle plate 446 ex tending between and suitably fixed to the side stantially U-shaped bracket 449 which in turn I is suitably fixed to the plate 446. The inner end of the stub shaft 448 carries an annular drive 'plate 450 formed of resilient material, such as rubber, leather or the like, which cooperates with the annular flange 440. The outer end of the stub shaft 448 carries a bevel gear 45! arranged in driven relation with respect to an associated bevel gear 452 carried by the drive shaft 153. It is noted that the drive shaft (5B is common to a plurality of switches of the character of the switch 400 and is suitably journaled in an external support, not shown. Preferably, the drive shaft |5B is driven in a clockwise direction, as viewed in Fig. 5, by a constant speed motor, not shown, such as a synchronous motor, whereby the speed of rotation of the drive shaft I5B is maintained within extremely close limits. It is noted that the bevel gear 45l is arranged in constant meshing relation with the bevel gear 452, whereby the stub shaft 448 is constantly driven in a clockwise direction, as viewed in Fig. 4, by .the drive shaft I5B.

Further, the switch 400 comprises a release the support "I, and an armature 456, the arma-' ture 456 being pivotally mounted on the outer end of the field element 455 by a pivot pin 451. The core 454 carries an operating winding 458 and a copper sleeve 458, the copper sleeve rendering the armature 456 slow to operate after the operating winding 458 is energized. The armature 456 is biased in a clockwise direction about the pivot pin 451, as viewed in Fig. 4, by

w an arrangement comprising a set of switch (ill the tubular collar v436 carries an annular flange springs B suitably secured to the field element 455, the individual switch springs in the set of switch springs 8513 being suitably insulated from each other and from the field element 455 by interposed strips of insulation 460. The outer end of the armature 456 carries a pawl 46l operatively associated with the ratchet wheel 453, whereby the ratchet wheel 453 may be freely rotated in a clockwise direction, as viewed in Fig. 4, when the armature 456 is released, but may be rotated in the counterclockwise direction, as viewed in Fig. 4, only when the armature 456 is operated.

At this point it is noted that the switch 400 as a whole is supported in cooperating relation with th drive shaft [5B upon an external support, not shown, whereby the bevel'gear 45| is arranged in meshing relation with th bevel gear 452, as previously noted. Also, the switch 400 may be removed as a whole from its external support relative to the drive shaft I5B, thereby. to facilitate replacement or repair thereof.

When the switch 400 is completely released the winding 4 of the go magnet 80B and the wind- .ing 443 of the stop magnet B are deenergized;

the operating shaft 406 is biased in a counterclockwise direction, as viewed in Fig. 4, by the spiral leaf spring 434; and the stub shaft 448 is driven at a constant speed in the clockwise direction, as viewed in Fig.4, by the constantly rotating drive shaft IB. When the switch 400 is thus completely released the tubular collar 436 I I and II the wiper set IOB occupies a position in occupies its retracted position toward the bottom,

respect to the contact bank 416, and its 'completely retracted positiontoward the bottom, as viewed in Fig. 5, with respect to the contact bank l6.

. Inorder to operate the switch 400, thereby to cause the wiper set MB to select a particular group or row of contact sets, the winding 4 of the go magnet 60B is first energized and retained energized for a corresponding given time ,interval, depending upon the speed of operation of the switch 400 relative to the speed of rotation of the stub shaft 446, this given time interval comprising one or more unit time intervals, as explained more fully hereinafter; at the conclusion'of this given time interval the winding 44! of the go magnet 80B isdeenergized and the winding 443 of the stop magnet 30B is energized.

longitudinal alignment with respect to a corresponding row of contact sets. Thus, at the conclusion of the first, second,'etc., and eleventh unit time intervals, the wiper set [03 occupies positions respectively disposed in longitudinal alignment with respect to the corresponding first, second, etc., and eleventh rows of contact sets.

At the conclusion of the given time interval the winding m of the go magnet 80B is deener giz'ed and the winding 443 of the stop magnet 90B is energized, as previouslynoted, whereupon the field element 444 of the stop magnet 90B attracts the annular flange 440, causing the tubular collar 436 and the annular flange-440 carried thereby to be moved toward the bottom, as viewed in Fig. 5, the pin and slot connection 431-438 between the operating shaft 406 and the tubular collar 436 energized, thereby to retain the annular flange 440 out of-engagement with th annular drive plate 450 and inlocke'd engagement with the field When the winding 4 of the go magnet 80B is thus energized the field element 442 thereof attracts the annular flange 440, thereby to cause the annular flange 440 to move toward the top,

as viewed in Fig. 5, into frictional engagement element'444. As long as the winding- 443 of the stop magnet 90B is retained energized, the annular flange 440 is retained in locked engagement with respect to the field element 444, thereby to retain the spiral leaf spring 434 in its wound con- .dition and to prevent unwinding thereof and the consequent rotation of the operating shaft 406 in a counterclockwise direction, as viewed in Fig. 4,

. in a manner more fully explained hereinafter.

annular flange 440 i thus moved bythe go mag-' net 603 into frictional engagement with the annular drive plate 450 the operating shaft 406 is rotated in a clockwise direction, as viewed in Fig.

4, with the stub shaft 448,'thereby to cause the spiral leaf spring 434 to be wound up.

At this time, the winding 426 of the shift magnet 303 is deenergized, whereby the armature 424 cupies its retracted position toward the bottom,

as viewedin Fig. 5, whereby the pin 4 carried by th operating shaft 406 engages the straight portion 430 of the spiral groove 5 cut in the cylindrical sidewall 4| I of the carriage 4l0.

As the operating shaft 406 is-rotated in a clockwise direction, as viewed in Fig. 4 at this time,

the pin 440 carried by the operating shaft 406 biased in a clockwise direction about the pivot pin 451, 'asviewed in Fig. 4, by the set of switch springs 953, Thus, the pawl 46! carried by the armature 456 engages one of the notches provided in the ratchet wheel 453, thereby positively to retain the spiral leaf spring 434' in its wound ,condition and positively to prevent unwinding thereof and the consequent rotation of the operating shaft 406 in a counterclockwise direction,

as viewed in Fig.2.

viewed in Fig.4, which motion constitutes the acts uponthe straight portion 430 of the spiral groove, 5 cut in the cylindrical side wall 4| [of the carriage to the operating shaft 406 for rotation therewith. Accordingly, the carriage 410 is rotated with the operating shaft 406, thereby to cause the wiper 4l0,' thereby to lock the carriage 410 set MB to be rotated below the lower ends of the various rows of contact sets without engagement therewith, whereby the wiperaset MB is moved progressively to select the various rows of contact sets in a continuous motion and at a uniform speed. The speed of rotation of the oper-- atingshaft 406 is so proportioned relative to the circumferentialspacing between the rows of. con tact sets that, at the conclusion of a given unit time interval, the-wiper set |0B occupies a position in longitudinal alignment with respect to the first row of contact sets 4 l8; and at the conclusion of any number of time intervals between pin 425, as viewed in Fig. 5, against the bias of the set of switch springs 353. When the armature 424 is thus operated the arm 429 car- 'ried thereby is forced against the bottom wall 2 of the "carriage H0 and exerts a lifting action thereon, whereby the carriage, M0 is lifted or slid longitudinally toward the top, as viewed in Fig. 5, thereby to disengage the pin 4 carried by the operating shaft 406 and the straight portion 430 of the spiral groove 6 cut in the cylindrical side wall '4 of the carriage M0, and to engage the pin 4 and the helical, portion of the spiral groove -4|5 cut in the cylindrical side wall 4. Also, .when' the carriage H0 is thus lifted or moved longitudinally toward the top. as viewed inFig. 5,the guide strip 42l' of the previously selected row of contact sets is forced between the individual wipers of the wiper set I013, thereby positively to lock the wiper set IIB and the carriage 0- against further rotation in the clockwise direction, as viewed in Fig. 4. At this time, the carriage H0 is adapted for longitudinal sliding movement toward the top,. as viewed in Fig. 5, along the operating shaft 406.

At this point, it is .noted that the winding 426 ofthe shift magnet B'is energized sub-' the operating shaft 406 and, consequently, the

carriage M0 and the wiper set [03 carried thereby is precisely centered by the action of the pawl 46! carried by the armature 456. This arrangement not only positively prevents effective unwinding of the spiral leaf spring 434, as pre-' viously explained, but it also positively insures that the wiper IOB occupies a position in precise longitudinal alignment with respect to the selected row of contact sets when the winding 426 of the shift magnet 30B is effectively energized and the armature 424 is operated, thereby insuring that the guide strip 42! is received in proper alignment between the individual wipers of the wiper set IOB.

Also, when the armature 424 of the shift magnet 303 is thus operated the set of switch springs B is operated, for a purpose more fully explained hereinafter.

After the switch 400 has been operated in the manner described above, thereby to select one of the rows of contact sets, in order further to operate the switch 400 to select a particular contact set in the previously selected row of 00m tact sets, the winding 443 of the stop magnet 90B is first deenergized and the winding 44lof the go magnet 80B is energized for a corresponding given time interval depending upon the speed of operation of the switch 400 relative to the speed of rotation of the stub shaft.446, this given time interval comprising one or more unit time intervals, as previously explained. At the conclusion of this given time interval the winding I of the go magnet 60B is deenergized andthe winding 443 of the stop magnet 60B is enerthe spiral groove 6 cut in the cylindrical side wall 4 of the carriage 0, the carriage H0 is lifted or slid longitudinally toward the top. as viewed in Fig. 5, along the operating shaft 406. As the carriage M0 is slid longitudinally toward the top, as viewed in Fig. 5, the guide strip MI 01' the previously selected row of contact sets is disposed between the individual wipers of the wiper set IOB carried by the carriage H0, thereby positively to prevent rotation of the carriage 410 and to insure continuous longitudinal sliding of the carriage H0 and the wiper set IOB carried thereby toward the top, as viewed in Fig. 5;

As the wiper set W3 is thus moved longitudinally toward the top, as viewed in Fig. 5, it progressively engages the individual contact sets in the previously selected row of'contact sets. As a previously noted, the line wipers of the wiper set IOB successively engage and disengage the vline contacts in the associated contact sets;

while the control wiper thereof bridges, the control contacts in the associated contact sets for a purpose more fully explained hereinafter.

The speed of rotation of the operating shaft 406 is so proportioned relative to the pitch of the spiral groove 415 out in the cylindrical side wall 4| I of the carriage H0 and the longitudinal spacing between'the individual contact sets in the row of contact sets that at the conclusion of a given unit time interval the wiper set IOB engages the first contact set in the previously selected row of contact sets, and at the conclusion of any number of unit time intervals between I and -l I,

gized. When the winding 443 of the stop magnet ner previously explained; whereby the operating shaft 406 is again rotated in the clockwise di-' rection, as viewed in' Fig. 4, with the stub shaft 448, thereby to cause the spiral leaf spring 434 to be further wound up. i

At this time the winding 426' of the shift magnet. 303 is energized and the armature 424 occupies its operated position, thereby to retain the carriage 410 in its lifted position, as viewed in Fig; 5. Accordingly, at this time, the helical portion of the spiral groove 5 cut in the cylindrical side wall 4 of the carriage 4I'0 operatively engages the pin 4 14 carried by the operating shaft 406, thereby to cause the pin 4 to ride in the spiral groove 4| 6. As the pin 4 carried by the operating shaft 406 rides in 75 the wiper set IOB engages a corresponding individual contact set in the previously selected row of contact sets. Thus at the conclusion of the first, second, etc., and eleventh unit time intervals thewiper set I-0B engages the corresponding first, second, etc., and eleventh individual contact sets in the previously selected row of contact sets.

At the conclusion of the given time interval the winding 4 of the go magnet 60B is deenergized and the winding 443 of the stop magnet 60B is energized as previously noted, whereupon the field element 444 of the stop magnet 903 attracts the annular flange 440, thereby to lock the spiral leaf spring 434' against unwinding and the consequent rotation of the operating shaft 406 in a counterclockwise direction, as viewed in Fig. 4. During the brief interval of time between the deenergization of the winding 44! of the go magnet 60B and the effective energization of the winding 443 of the stop magnet 603 the spiral leaf spring 434 tends to unwind, thereby to rotate the operatin shaft 406 in a counterclockwise direction, as view in Fig. 4. However, the spiral 'leaf sp ing 404 is prevented from effective unwinding; and the position of the operating shaft 406, and,-consequently, the longitudinal position of the carriage H0 and the wiper set [018 I carried thereby is precisely centered by the action of the pawl 46f carried by the armature 466 of the release magnet NB. This arrangementnot only positively prevents effective unwinding of the spiral leaf spring 434, as previousmentioned, thereby to establish a shunt connection between the pairs of individual contacts in the selected contact set. The switch 400 i retained in itsoperatedlposition so long as the winding 443 of the stop magnet B is retained springs is removed from between the individual wipers of the wiper set I03, thereby to unlock the carriage 0 for rotation in a c'ounterclockwise direction, as viewed in Fig. 4. Also, when energized, and the winding 450 01 the release magnet 66B is retained deenergized, thereby to prevent unwinding of the spiral leaf spring 404 in an obvious manner.

It is noted that during the first motion of the switch 400 when the carriage-4M is rotated in a clockwise direction from its normal position at the left toward the right, as viewed in' Fig. 4, the

first motion normal switch 403 is operated by the projection 433'carried by the cylindrical side wall 4 of the carriage 0. In the event that the carriage H0 is rotated in a clockwise direction, as viewed in Fig. 4, to a position disposed in longitudinal alignment with the eleventh row of con: tact sets, the first motion, limit-switch 00B is operated by the projection 403 carried by the cylindrical side wall 4| l of the carriage 4l0. Similarisn. during the second motion of the switch from its normal position at the bottom toward the top, as viewed in Fig. 5, the second motion normal switch 603 is operated by the top wall 4l0of the carriage 0. In the event that the carriage 0 is moved longitudinally toward the top, as viewed in Fig. .5, into engagement with the eleventh contact set in the previously selected row of contact sets, the second' motion limit switch 10B is .operated by the top wall 0 of the carriage 4I0.

In order completely to release the switch 400 I after it has been fully operated in the manner 400 when the carriage 0 is slid longitudinally when the carriage 4| 0 is moved from its final initially. Also, when the armature 424 of the previously explained, it is necessary not only to deenergize the winding 440' of the stop magnet 003 but also to energize'the winding 450 of the release magnet 653. When the stop magnet 60B is thus released the operating shaft 406 is rendered free to rotate in the counterclockwise direction, as'viewedin Fig; 4, except for the engagement between the pawl 46f and the asso-- ciated notch provided in the ratchet wheel 453. When the winding 456 of the release magnet 85B is thus energized the armature 456' is operated, thereby to operate the associated set of switch springs 05B and to cause the armature 456 to be rotated in a counterclockwise direction about the pivot pin 451, as viewed in Fig. 4, whereupon the the carriage H0 is returned to its normal position at the bottom, as viewed in Fig. 5, the pin 4 carried by. the operating shaft 406 disengages' the helical portion of the spiral groove cut in the cylindrical side wall 4 of the carriage 4!!! and reengages the straight portion 430 of the spiral groove 5, thereby to lock the carriage 410 against longitudinal sliding movement on the operating shaft 406 incident to the next cycle of motion normal switch 40Bis operated. Of course,

the second motion limit switch 103 is operated top position, as viewed in Fig. 5, in the event that the carriage M0 was so moved as tooperate the second motion limit switch 103 initially; 'similarly, the first motion limit switch 603 is operated when the carriage H0 is moved from its final position at the right, as viewed in Fig. 4,;

in the event that the carriage M0 was so moved as to operate the first motion limit switch 503 shift magnet 30B is released the set of switch springs 35B is operated in an obvious manner.

Fnally, when the carriage H0 is returned both to its normal position at the bottom, as viewed in Fig. 5, and to its normal position at the left; as

, viewed in Fig. 4, the winding of the release pawl 46l disengages the associated notch in the ratchet wheel 453. At this time the operating shaft 406 is free to rotate in a counterclockwise direction, as viewed in Fig.4, and is so rotated by the spiral leaf spring 404 incident. to the unwinding thereof. Accordingly, as the operating shaft 406 is rotated in a counterclockwise direction, as viewed in Fig. 4, the carriage 4l0,,is slid longitudinally along the operating shaft 406 from I the top toward the bottom, as viewed in-Flg. 5,

due to the cooperation between the pin 4 carried by the operating shaft 406 and the spiral groove 6- cut-inthe cylindrical side wall 4 of the carriag 0, in the manner previously explained.

magnet 85B is deenergized, thereby to release the armature 456, whereupon the armature 456 is rotated in a clockwise direction about the pivot pin 451, as viewed in Fig. 4., At this time the set of switch springs-95B is again operated and the pawl 46l carried by the armature 466 reengages one of the notches provided in the ratchet wheel 460 carried by the operating shaft 406, whereupon the operating shaft 406 is again locked against I rotationin a counterclockwise direction, as viewed in Fig. 4. At this time the switch 400 is completely released and available for further use.

Connection and arrangement of the telephone system Referring now more particularly to Figs, and 'I of the drawings, there is illustrated an automatic telephone system comprising an exchange having a plurality of subscriber lines ex- *tending thereto, including the subscriber lines When the carriage4l0 is returned almost to its normal position at the bottom, as viewed'in Fig. 5, the 420 of the shift magnet #03 is deenergized, whereupon the armature 429 is released in order to permit the carriage 0 to be moved into its normal position. When the carriage H0 is moved intoits normal position at the bottom, as viewedin Fig. 5, the guide strip 42l of the previously selected row of switching 60! and ml respectively extending to the sub scriber substations TI and T2. Also the exchange comprises subscriber controlled switching apparatus for setting -.up connections between various subscriber lines, this switching apparatus comprising a line switch individual to each,

subscriber line, the line switches 602 and I02 being individual to the subscriber lines 60! and "I, respectively, a group of selectors, including the selector 600, and a plurality of groups of connectors, one group of connectors including the connector'100. The number of selectors in the group of selectors and the number of connectors in each group of connectors in the system are determined in accordance with the maximum volume of traffic the exchange is required to handle. Preferably, each of the line switches-has access to each of the. selectors; each of the selectors has access to each of the connectors; and each of the connectors has access to each 01. the subscriber lines in an associated group.

Preferably, each subscriber substation comprises substation apparatus identical to that iilustrated at the subscriber substations Ti and T2; the subscriber substation apparatus at the subscriber substation Ti including atransmitter 603, a receiver 604, a hook switch 605 and a calling device 606; and the subscriber substation apparatus at the subscriber substation T2 includes a transmitter 103, a receiver 104, a hook switch 105 and a calling device 106. Preferably, the subscriber substation apparatus at each subscriber substation is entirely conventional with the exception of the calling device; while each calling device embodies the unique construction and arrangement disclosed in Bernard D. Willis Patent No. 2,222,131, granted November 19, 1940. As disclosed in the Willis patent, this calling device is so constructed and arranged that it transmits a single impulse of variable length or time duration, as contrasted with conventional calling devices which transmit a variable series of impulses, this calling device including a finger dial and having the same general external appearance of a conventional calling device.

Preferably, each line switch is identical to the line switches 602 and 102, which line switches are connected and arranged in accordance with conventional-practice.

Preferably, each of the selectors is identical to the selector 600 which comprises either an automatic switch of the character of the automatic switch I00, shown in Figs. 1 to 3, inclusive, or an automatic switch of the character of the automatic switch 400, shown in Figs. 4 and 5. This automatic switch comprises a go magnet 80X, a

stop magnet 90X, a shift magnet 30X, 9. wiper elements previously described in the automatic switch 400, corresponding reference characters being em loyed. Further, the connector 100 comprisesv a group of relays including a line relay R110, a hold relay R120, a test relay R130, an answer relay R140, 9. switch relay R160, a ring relay R160, and two control relays R110 and R180, and a control network.'

Operation of the apparatus incorporated in the system The mechanical construction and arrangement of the automatic switch I00, shown in Figs. 1 to 3, inclusive, and the automatic switch 400, shown inFigs. 4 and 5, as well as the electrical connection and arrangement or the telephone system shown in Figs. 6 and '1, will best be under-' stood from a consideration of the mode of operation of the apparatus incorporated in the system incident to the extension of a telephone connection from the subscriber substation TI to the subscriber substation T2.

A call is initiated at the subscriber substation TI by removing the receiver 604 of the telephone instrument thereat from its associated switchhook, thereby to cause the hook switch 606 to operate and complete an obvious connection between the line conductors of the subscriber line 60! terminating in the line switch 602. When a connection is completed between the line conductors of the subscriber line 60l, the line switch 602 operates automatically to search for a trunk extending to an idle selector, in accordance with conventional practice. Assuming that the selector 600 is the first idle selector accessible to the line switch 602, the line switch 602-operates thereof.

to seize the trunk 060 extending thereto, the trunk 660 being marked as idle by the absence of potential upon the control conductor 663 I When the line switch 602 seizes the trunk 660, further operation thereof is arrested of switch springs; 05X are provided, these elements corresponding in functionto the corresponding elements previously described" in the automatic switch 400, corresponding reference characters being employed. Further, the selector 600 comprises a group of relays including a line relay R6l0, a hold relay R620, a switch relay "R630, and two control relays R640 and R660, and a control network.

Preferably, each of the connectors 'is identical to the .connector 100 which comprises either an automatic switch of the character of the automatic switch I00, shown in Figs. 1 to 3, inclusive, or an automatic switch oi the character of the automatic switch 400, shown in Figs. 4 and 5.

wiper set IOY, a first motion normal switch "Y,

a first'motion limit switch MY, 9. second motion' normal switch Y. a second motion limit switch R640 and the stop magnet 00X to battery. Also,

and it' operates to switch through, thereby to complete an obvious connection between the subscriber line 601 and the line conductors C66I and C662 01 the trunk 660. When this connection is completed an obvious loop circuit is completed between'the calling subscriber'substation TI and the upper and lower windingsoi the line relay R6l0 in the'selector 600 by way of the line switch 602. When thus energized the relay R6l0 operates to complete, at the contacts 6| 1, a circuit for energizing in series the winding 01 the control relay' R640 and the stop magnet 60X, this circuit extending from ground by way ofthecontacts 66l and 6, the winding of it is noted that the winding'oi the control relay R640 is normally-shunted by the contacts 641 and the resistor 645, this arrangement being previouslymentioned shunt around the winding thereof, whereby an obvious holding circuit submatic switch incorporated in the selector 600 is stantially identical to that previously traced is completed for energizing inseries the winding of the control relay R640 and the stop magnet X.

When thu's energized .the stop magnet 90X.op-

erates, thereby to insure that the automatic switch incorporated in the selector 600 is declutched from the associated drive shaft. Also, upon operating, the line relay R6l0 completes at the contacts 612 an obvious circuit for energizing the winding of the hold relay R620, thereby to cause the latter relay to operate. Upon operating, the hold relay R620 completes, at the contacts 622, an obvious-multiple point in the previously mentioned holding circiiit for energizing in-series the winding of the control relay R640 and the stop magnet 90X. Also, the hold relay R620 completes, at the contacts 62l, an obvious path for applying ground potential to the control conductor C663 of the trunk 660,

thereby to mark the trunk 660 as busy to the line switches having access thereto. Further, when ground potential is applied to the control conductor C663 of the trunk 660, it is applied by I way of the line switch 602 to the control conductor C60l of the subscriber line 60!, thereby to mark the subscriber line'60l as busy to the connectors having access thereto. At this time an operative connection is completed betweenthe calling subscriber substation TI and the selector 600, and the selector 600 is'in readiness to receive the first digit.

The subscriber at the calling subscriber substation TI then dials the first digit in the calling device 606 thereat, thereby to cause the previously traced connection between the calling clutched to the associated drive shaft, whereupon the first motion thereof is initiated in the a manner previously explained, whereupon, the first motion normal switch 40X is operated. when the first motion normal switch 40X is thus operated there is completed, at the contacts 43 thereof, an obvious alternative path for applyingground potential to the control conductor C663 of the trunk 660, thereby to retain both the trunk 660 and the calling subscriber line 60! marked as busy, as previously explained. Also, at the contacts 42 of the first motion normal switch 40X, there is completed a holding circuit for energizing in series the winding'of the control relay R650 and the go magnet 80X, this circuit extending from ground by way of the contacts 6l3, the contacts 12 of the second motion limit switch 10X, the contacts 42 of the,.first motion normal switch 40X, thecontacts 653, the winding of R650 and the go magnet 00!! to battery.

Also, upon restoring, the line. relay R6l0 interrupts, at the contacts 6 l2, the previously mensubscriber substation 'TI and the line relay R6l0 in the selector 600 to be interrupted, to remain interrupted for a corresponding given time interval, and then to be recompleted at the conclusion of the given time interval, the duration of the given time interval being determined by the particular digit dialed in the calling device 606 at the calling subscriber substation Tl, as

disclosed in the previously mentioned Willis patent. Accordingly, the line relay R6l0 restores,

remains. restored for the given time interval and then reoperates. Upon restoring, the line relay R6l0 completes, at the contacts 663, a circuit for energizing .in series the windingof the control relay R650 and the go magnet 00X, this circuit extending from ground by way of the contacts M3 and 623, the contacts 62 of the second motion normal switch 60X, the winding of R650 and the go magnet 30X .to battery. It

is noted that the winding of the'control relay R650 is normally'shunted by the contacts 652 and' the resistor 655, this arrangement being provided in order positively to insure that the go magnet 80X is fully energized promptly.-

When thus energized the control relay' R650 operates to interrupt, at the contacts 652, the

previously mentioned shunt around the windin thereof, whereby an obvious holding circuit substantially identical to that previously traced is completed for energizing in series the winding of the control relay R650 and the go magnet X.

Also, the control relay R650 interrupts, at the contacts l, the previously traced holding circuit for energizing in series the winding of the control relay R640 and the stop magnet f 60X, thereby to cause the control relay'R640 to restore and the stop magnet 00X to release.

When the stop magnet 00X is thus released and the go magnet 60!! is thus operated, the autoapplying ground potential to the control conductor C663 of the trunk 660, and interrupts, at the contacts 623, the previously traced original circuit for energizing in series the winding of the control relay R650 and the go magnet 00X.

Accordingly, at this time the wiper set IOX of the automatic switch incorporated in the selector 600 is being driven continuously .in, the first motion, in the manner previously explained; and

continues to be so driven until the conclusion of the first digit, whereupon the line relay R6 l0 reoperates as previously explained. Upon reoperating, the line relay R6l0 interrupts, at the contacts 613, the ,previously traced holding circuit I for energizing in series the winding of the control relay R650 and the'go magnet 00X, thereby to cause the control relay R650 to restore and the go magnet X to release. ,Upon restoring,

the control relay R650 completes, at the contacts 65l, the previously traced original circuit for energizing in series the winding of the control relay R640 and the stop magnet X, thereby to cause both the control relay-R640 and the stop magnet 30X to reoperate. Upon reoperating, the stop magnet 00X declutches the automatic-switch incorporated in the selector' 600 from the assoelated drive shaft, thereby positively to arrest further operation thereof in the,first motion, in

the manner previously explained. Upon, uponreoperating, the line relay R6l0 recompletes, at the contacts M2, the previously mentioned circuit for energizing the winding of the hold relay R620, thereby to cause the latter relay to reoperate in the event it restored during the first digit. Upon reoperating, the control relay R640 completes, at the contacts'643, a circuit for energizing the shift magnet 30X, this circuit extending from ground by way ofthe contacts 643, the contacts 4| of the first motion normal switch 40X, and the shift magnet tax to battery. When thus energized, the shift magnet 30X operates to 

